Lung cancer is the leading cause of cancer death in the United States in both men and women. Efforts to treat the advanced disease process have marginally enhanced survival over the last forty years. A reduction in mortality rates are likely to arise from strategies which prevent the disease, enable its recognition early, or enable its treatment successfully. Therefore, novel rational treatment strategies, including gene therapy approaches, are being actively investigated. Although gene therapy is an arena with great potential, to date, its efficacy has been limited. We believe that this lack of efficacy exists primarily because of limitations in therapeutic gene delivery. Our objective is to understand and overcome limitations in gene transfer as they pertain to a model of advanced (malignant pleural effusions) non-small cell lung cancer (NSCLC). Towards this aim, this project is a direct extension of investigations performed by the PI to study the mechanisms whereby adenoviral vectors transport genes into lung cancer cells. Preliminary studies suggest that NSCLC is heterogeneously transduced by the adenoviral (Ad) vector, partly because the cancer cells differ in their ability to bind and internalize the virus. In addition, with respect to in vivo transduction, there are inhibitory soluble factors within the tumor milieu that impede gene transfer by Ad-vectors. The current study aims to characterize the physical properties and mechanisms underlying the inhibition, and to possibly identify the factors which impair Ad-gene transfer in malignant pleural effusions. In addition, the proposal seeks to extend on the principles responsible for mediating efficient gene transfer into lung cancer cells, specifically, how important entry is to Ad-transduction. We believe that the identification of the relevant hurdles to gene therapy will better enable us to develop strategies to overcome those limitations, or to exclude the current generation of Ad-vectors as viable candidates for comprehensive gene therapy of lung cancer.